The Potatoe Plague. (E: 
the germinating seed, which diastase assists in the conver- 
sion of starch into the gum, sugar, &c., which are required 
for the nourishment of the young shoot. The potatoe con- 
tains a very small per centage of nitrogenous matter. I 
would, therefore, venture the suggestion that the great addi- 
tion made in the process of ripening, to the already large stock 
of starch contained in the tuber, may be more than can be 
converted into the gum, sugar, &e., by the small quantity of 
diastase generated in the germinating potatoe. If this be the 
case, then it would follow that the diastase being mixed with 
too large a proportion of starch (like leaven mixed with too 
large a proportion of dough) only does its work imperfectly, 
and the result is a weakly shoot, whilst a portion of the 
starch, failing to receive the vitalizing influence of the dias- 
tase, undergoes the natural course of decay, and produces the 
symptoms peculiar to dry-rot, wet-rot, or curl. This suppo- 
sition is, of course, pure theory, and must not be confounded 
with the facts on which it is based. To make it quite clear 
where the one ends and the other begins, I will very briefly 
recapitulate. Facts have been brought forward to prove that 
ripe sets are subject to curl, and vice versa, also that a large 
addition is made to the quantity of starch in the potatoe in 
the process of ripening. Direct experiment also proves that 
“diastase” is required for the germination of seeds, which 
diastase can only be formed from some substance containing 
nitrogen ; potatoes contain a very small proportion of such sub- 
stances, and therefore can have but very little diastase. Here 
our facts end, but from these premises I would hazard the 
deduction that if we allow our seed potatoes to ripen, they 
acquire more starch than can be made available to the grow- 
ing shoot; which excess naturally decays, and then infects 
and injures, or even destroys, the plant with which it is con- 
nected. <A similar effect is produced in the human subject 
when more food is taken into the stomach than the gastric 
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